1. Field of the Invention
The invention pertains to a crankshaft, especially to an eccentric shaft for an internal combustion engine, especially for a rotary combustion engine, the working unit of which comprises essentially a peripheral housing, side housing plates, and a piston, which is supported on an eccentric of the eccentric shaft, the tips of the piston rotating along an epitrochoidal orbit inside the peripheral housing to form three separate working spaces, where the rotary piston engine can have several working units.
2. Description of the Related Art
Rotary combustion engines of the conventional type have eccentric shafts which consist of a heat-resistant steel with a hardenable surface, the final form of the eccentric shaft being produced from the solid rough forging by turning, case hardening, and grinding. The most common rotary piston engine being built today is an engine with two working units; that is, the eccentric shaft has two eccentrics, each of which has its own eccentric bearing, and on each of which a piston is supported. Each piston rotates in its own housing, consisting of a peripheral housing and two side housing plates. At the point where the two working units are connected, the side housing plates in question merge into a single center plate, which has a main bearing just as the outer side housing plates have.
The solid eccentric shaft has a bore drilled through its center to allow passage of lubricating oil, which is sent by an oil pump from a supply tank to the main bearings and to the eccentric bearings. The lubricating oil is introduced from an annular channel radially on the outside into the central bore. It is, of course, expensive to produce an eccentric shaft of this type, but in addition little or no advantage can be taken of the ability of the lubricating oil to cool the eccentric shaft, because the amount of heat which can be dissipated across the surface of the relatively small central bore is very low.